Module 7: Rational Functions and Function Operations

 

 

In Try This 2 you may have noticed that the rules of transformations apply to rational functions the same way they apply to the other functions you have worked with in this course. As an example, you explored a rational function of the form  because it allows you to work with transformations relatively easily. Some characteristics of the graph of a function of the form  are listed in the chart shown.

 

Rational Functions of the Form

Vertical Stretch

There is a vertical stretch by a factor of a.

Horizontal Asymptote

The horizontal asymptote is translated k units up or down from the original location of y = 0. The horizontal asymptote is y = k.

Vertical Asymptote

The vertical asymptote is translated h units right or left from the original location of x = 0. The vertical asymptote is x = h.

Domain

The domain is any real number, except h. This restriction is because x = h (the vertical asymptote) will result in an undefined value.

Range

The range is any real number, except k. This restriction is because the horizontal asymptote is y = k.


An example of a graph of a rational function   follows.

 

 

This diagram shows the function y equals three divided by all of x minus 1, and then all added by 2. The range, domain, vertical asymptote, and horizontal asymptote are labelled on the graph.